gsminmag Mineralogical Magazine Mineralogical Magazine 0026-461X Mineralogical Society 10.1180/minmag.1980.043.332.08 Zoisite-Clinozoisite Relations in Low- to Medium-Grade High-Pressure Metamorphic Rocks and Their Implications Enami Masaki Department of Earth Sciences, Nagoya University, Nagoya 464, Japan Banno Shohei Department of Earth Sciences, Kanazawa University, Kanazawa 920, Japan 12 1980 43 332 1005 1013 15 11 1079 5 6 1980 Copyright © 1980, The Mineralogical Society 1980 Summary

Coexisting zoisite and clinozoisite in seventeen specimens from six localities in Japan have been studied with the electron-probe microanalyser. Zoisite and clinozoisite are commonly zoned, but compositional gaps between them are systematic. Referring to the metamorphic grade of the host rocks, a temporary and schematic phase-diagram for the system Ca2Al3Si3O12-(OH)-Ca2Al2Fe3+Si3O12(OH) is presented. With increasing temperature, in the range of low- to medium-grade metamorphism, the compositional gap between the two epidote-group minerals shifts towards higher Fe3+ compositions.